Casing suspension system



United States Patent O 3,105,552 CAING SUSPENSION SYSTEM John A. Haeber and Lloyd G. Gtternan, Houston, Tex., assignors to Shell (lil Company, New York, N31., a corporation of Delaware Filed July 27, 1960, Ser. No. 45,646 4 Clmms. (Cl. 16o-'75) This invention relates to apparatus for use on oil and gas well installations and pertains more particularly to apparatus for suspending multiple strings of well casing and/ or tubing within a well from a well casinghead and/ or a casing and tubing suspension body. The present invention is especially concerned with a casing suspension system for use in underwater wellhead installations.

In an attempt to locate new oil fields an increasing amount of well drilling has been conducted at offshore locations, such for example, as oilc the coast of Louisiana, Texas and California. As a general rule, the strings of casing in a well, together with the tubing stringr or strings, extend to a point well above the surface of the water where they are closed in the conventional manner that is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Attempts have been made recently to provide methods and apparatus for drilling and completing a well wherein both the well casinghead and subsequently the wellhead assembly and casinghead closure device are located underwater at a depth sufhcient to allow ships to pass over them. Preferably, the casinghead and wellhead closure assemblies are located close to the ocean floor. In order to install equipment of this type underwater in depths greater than fthe shallow depths at which the diver can easily operate, it has been necessary to design entirely new equipment for this purpose. Thus, after drilling and completing an oil or gas well at an offshore location in a manner described in copending patent application, Seri-al No. 830,538, filed July 30, 1959, and entitled Underwater Well Completion Method, of which this application is a continuation-impart, the casing in the well may be suspended from the well casinghead by the equipment of the present invention.

It is an object of the present invention to provide a casing suspension system whereby multiple strings of casing may be nested within each other and securely anchored within the casinghead in the manner whereby well pressures or thermal expansion of the casing strings cannot cause the casing strings to move upwardly within the well.

Another object of the present invention is to provide apparatus for hanging one string of casing or tubing within another string of casing with the top of each string of casing and/or tubing being independently anchored to the inner wall of a well casinghead.

A further object of the present invention is to provide a casing suspension system wherein a casing hanger having a string of casing suspended therefrom is seated in a uidtight manner within a well casing head, and a casing and/or tubing hanger having a string of casing or tubing suspended therefrom is seated in a fluidtight manner within the iirst casing hanger, with both casing hangers being independently anchored to the inner wall of the casinghead in a manner such that any well pressures or thermal expansion of the casing strings does not cause either casing hanger to move off its seat.

-Still another object of the present invention is to pro- Vide a casing suspension system incorporating at least a pair of casing and/or tubing hanger which may be run into the well one at a time with the same running tool.

Another object of the present invention is to provide a casing suspension system employing at least two con- 3,ld5,552 Patented Oct. 1, 1963 centric strings of casing with the innermost casing string being provided with a casing hanger adapted to receive therethrough and seat therein one or more tubing strings.

These and other objects of this invention will be understood from the following description taken with reference to the drawing wherein FIGURE l is a diagrammatic view, taken in longitudinal cross-section of a casing suspension system mounted within a well casinghead of the present invention, and FIGURE 2 is a fragmental view taken in longitudinal cross section of another form of a well casinghead.

lReferring to the drawing, a typical underwater well installation incorporating the apparatus of the present invention comprises an underwater casinghead 11 having a casing and tubing suspension body 12 positioned therein on a seat 13. A series of strings of casing 14 and 15 are suspended within the casing and tubing suspension body 12 from suitable hangers 17 and 18. lf desired, the outermost casing 16 may be threaded or welded, as at 19, to the lower end of the casing and tubing suspension body 12. While the casinghead 11 is illustrated with a casing and tubing suspension body 12 suspended therein, in some installations the casing and tubing suspension body may form an integral part of the casinghead 11 as shown in FIGURE 2. The casinghead 11 extends upwardly from a suitable support member, such as a horizontal plate 21 which preferably rests or is cemented to the ocean oor in an underwater well installation. A string of conductor pipe or surface casing 22 is generally secured to the bottom of the casmghead 11, as by welding, and extends into and is preferably cemented in the well drilled in lthe ocean oor.

The upper end of the casing and .tubing suspension body 12 may be closed in any suitable manner, as by a casinghead closure body 20 having one or more vertical bores 23 and 24 therein. A wellhead closure assembly of this type is shown and described in copending patent application, Serial No. 834,096, `filed August 17, 1959, and entitled Wellhead Assembly Lockdown Apparatus. The casinghead closure 20 is provided with a circumferential expansible seal 25 and a series of radially-expanding locking clogs 26 adapted to engage one or more locking grooves 27 formed in the inner wall of the casing and tubing suspension body 12. Due to the weight of flow control equipment generally installed above the casinghead closure 2l), a seating shoulder 28 is formed within the casing and tubing suspension body 12 for seating the casinghead closure rather than seating .fthe entire weight of the assembly within the uppermost casing hanger 16, which would be an alternative arrangement. In one arrangement of the present invention the casinghead closure 20 has a downwardly extending adaptor 31 from which a pair of tubing strings (not shown) may be suspended, as by threaded connections at 32 and 33. O-ring seals 34 or any other sui-table means are provided on the outer surface of the adaptor 31 near the lower end thereof, or on the inner surface of the hanger 17, for forming a fluidtight seal between the lower end of the adaptor and the uppermost casing hanger 17.

The uppermost casing hanger 17 may be provided with a seating shoulder or surface 37 on the inner surface thereof for seating the lower end of the adaptor 31, if desired, or for seating any other suitable type of tubing hanger. A shoulder 40 is formed on the outer wall of the casing hanger 17 and is adapted to seat on a cooperating shoulder or seating surface 41 formed on the inner Wall of the lower casing hanger 18, with seals 42 being preferably provided for forming a lluidtight seal. Seals 42, 45, 47 and 4S are compression type packings, but could be -O-rings or quad rings.

The outer surface of the casing hanger 18 is in turn provided with a seating shoulder 43 adapted to seat on a cooperating seating surface or shoulder 44 formed on the inner surface of the casing and tubing suspension body 12. Seals 45 are provided for forming a iluidtight seal between seating surfaces 43 and 44. A large O-ring seal or other type packing member 46 is preferably provided between the casing and tubing suspension body 12 and the casinghead 11 with auxiliary seals 47 and 48 being provided in the seating surface or shoulder 51 on the lower end of the casing and tubing suspension body 12 which engages the seating shoulder 13 on the inner wall of the casinghead 11. As mentioned hereinabove in many well installations, especially those used on land, the casing and tubing suspension body 12 may be welded to or form an integral part of the casinghead 11. However, for ease in drilling and completing a well at an offshore location with the wellhead located underwater on the ocean floor, it is preferred, in such an installation, to have the casing and tubing suspension body 12 releasably secured to the casinghead 11. The casing and tubing suspension body 12 is preferably provided with a series of spring-loaded hold-down slips 52 which are adapted to engage the inner wall of the casinghead 11 and hold the tubing and casing suspension body rtherein against any pressures tending to force it upwardly therefrom. The casinghead 11 rnay also be provided with one or more grooves 53 on the outer surface or on the inner surface thereof for latching a running tool thereto when the casinghead is originally installed. Although the casinghead 11 is shown as being provided With a port 54 in the wall thereof, this iluid port 54 is normally closed by a suitable valve (not shown) during drilling operations and after the completion of the well.

The casing hangers 17 and 18 are provided with hold down slips 57 and 5S which are mounted on the outer surface of the hangers 17 and 18 in a manner so as to engage the inner wall of the casing and tubing suspension body 12 at vertically spaced points. Thus, the casing strings 14 and 15 are independently anchored, through their casing hangers 17 and 1S, to the casing and tubing suspension body 12 against forces, such as Well pressure or thermal expansion of the casing strings, tending to raise the casing strings 14 and 15 within the well. lt may be seen that the hold-down slips 58 are only subject to pressures within the annulus 59 between casing strings 15 and 16 which tend to move the lower casing hanger 1S olf its seat 44. On the other hand, if the upper casing hanger 17 was anchored to the lower casing 18 as well as being seated therein, the lower hold-down slips S would be subjected to pressures within the annuli 59 and 60 between casing strings 14, and 16.

The casing hangers 17 and 18 are provided on their inner surfaces near the top thereof with one or more grooves 61 and 62, respectively, to which a latching tool can be secured for lowering the casing hangers 17 and 18, and the casing strings 14 and 15, secured thereto, down into a Well. It is preferred that both the casing hangers 17 and 18 have the same internal diameter near the top of the bore therethrough, that is, opposite the latching grooves 6,1 and 62, so that the same running tool (not shown) may be employed to run both casing hangers 17 and 18 into the casing and tubing suspension body 12. Additionally, it will be seen that by designing the upper casing hanger 17 so that the hold-down slips 57 thereof contact the inner surface of the casing and tubing suspension body 12, a substantial portion of the bore through the casing hanger 17 may be enlarged, as at 63 so as to accommodate an adapter 31 from which one or more tubing strings (not shown) may be suspended. Alternatively, since additional room is provided in the casing hanger -17 by the enlarged bore 63, another casing or tubing suspension head or hanger could be seated therein to suspend a string of tubing of fairly large diameter.

We claim as our invention:

l. A wellhead apparatus adapted to be positioned at the top of a well for suspending a combination of tubing and casing strings in :the well, said apparatus comprising a casinghead nxedly positioned coaxially over said well, said casinghead having at least one seating shoulder formed therein, a rst casing hanger having seating shoulders formed on the inside and outside thereof, said outside shoulder being formed to seat on a shoulder within the casinghead, a rst string of casing secured to and suspending from the rst casing hanger, a second casing hanger having seating shoulders formed on at least the outside thereof, said outer shoulder being formed to seat on the shoulder within said rst casing hanger, a second string of casing secured to and suspending from the second casing hanger, and hold-down slip means carried outwardly by each of said casing hangers and positioned to engage the inner surface of said casinghead.

2. A wellhead apparatus to be positioned at the top of a well for suspending a combination of tubing and casing strings in the well, said apparatus comprising a casinghead xedly positioned coaxially over said well, said casinghead having at least one seating shoulder formed therein, a rst string of casing suspended in said well with the top of said casing secured to the lower end of said casinghead, a first casing hanger having seating shoulders formed on the inside and outside thereof, said outside shoulder being formed to seat on a shoulder within the casinghead, a second string of casing secured to and suspending from the rst casing hanger, a second casing hanger having seating shoulders formed on the inside and outside thereof, said outer shoulder being formed to seat on the shoulder within said rst casing hanger, a third string of casing secured to and suspending from the second casing hanger, hold-down slip means carried outwardly by each of said casing hangers and positioned to engage the inner surface of said casinghead, and closure means removably secured to the upper end of said casinghead.

3. A wellhead appanatus adapted 4to, be positioned at the top of ia well for suspending a combination of tubing and casing strings in the well, said apparatus comprising a casinghead `iixeidly positioned iooaxially over said well, said casinghead including a casing and tubing suspension body secured in ya uidtight manner to said oasinghead and having at least one seating shoulder formed therein, a first string of casing suspended in said well with the top of said casing secu-red to the lower end of said casing and tubing lsuspension tbody, seal moans yclosing the space between said oasinghead and said casing and tubing suspension body, .a -rst casing hanger having seating `shoulders formed on atlie inside and outside thereof, said outside shoulder #being formed to seat on Ia shoulder rwithin the casing and tubing suspension body, a second string of casing secured to land suspending nrorn the first casing lChanger, la second casing hanger having seating shoulders formed on thei inside land outside thereof, said outer shoulder being formed to seat on the shoulder ywithin said rst casing hanger, a third string .of casing secured to and suspending rom the second casing hanger, Ihold-down slip melans carried outwardly by each yof said casing hangers and positioned to engage the inner surface of said oa'sing and tubing suspension body, and closure moans removably secured to the upper end of said casing `and tubing sus iension body.

4. A wellhead Iapparatus adapted to be positioned at the top fof la well for suspending a `combination od tubing and casing strings in the well, said lapparatus comprising a casinghead fxediy positioned coaxially over said well, said casinghead including a casing and tubing suspension body secured in la liuidtight manner to said casinghead and having yat least one seating shoulder formed therein, a first string of casing suspended in said well with the top of said casing secured to the lower end of said easing and tubing suspension body, seal means closing the space between said oasinghead and said lcasing and tubing suspension body, a rst casing hanger having seating shoulders formed on the inside and outside thereof, said outside shoulder being Iformed to seat `on shoulder Within the casing and tubing suspension body, la second string of casing ysecured to and suspending `from the rst easing hanger, a second casing hanger having seating shoulders formed on the inside and outside thereof, said outer shoulder being formed to seat on the shoulder Within said rst casing hanger, a third string of casing secured to and suspending from the second oasing hanger, hold-down slip means carried outwardly by each `of said casing hangers and positioned to engage the inner sur-face of said casing and tubing suspension body, each `of said casing hangers having a bore therethrough the upper ends of which are of the same diameter, groove latch means formed on the inner wall of said bore near the upper end thereof for securing 'a tool thereto, connector means oamed by each casing hanger for securing iat least one casing string thereto, he inner bone of said second ldasing hanger being adapted to receive `sind seal therein in a fluidtight manner the upper end :of at least one tubing string, and closure means lremovably secured to :the upper end of said easing Iand. tubing suspension body.

References Cited in the le of this patent UNITED STATES PATENTS 1,587,441 Taylor June 1, 1926 1,811,013 Hum-alsof: June 23, 1931 1,849,374 McEvoy et al Mar. 15, 1932 1,906,265 Hild May 2, 1933 2,034,698 H-ild Mar, 24, 1936 2,118,694 McDonough et lal Muy 24, 1938 2,589,483 Eckel et al. Mar. 1S, 1952 

1. A WELLHEAD APPARATUS ADAPTED TO BE POSITIONED AT THE TOP OF A WELL FOR SUSPENDING A COMBINATION OF TUBING AND CASING STRINGS IN THE WELL, SAID APPARATUS COMPRISING A CASINGHEAD FIXEDLY POSITIONED COAXIALLY OVER SAID WELL, SAID CASINGHEAD HAVING AT LEAST ONE SEATING SHOULDER FORMED THEREIN, A FIRST CASING HANGER HAVING SEATING SHOULDERS FORMED ON THE INSIDE AND OUTSIDE THEREOF, SAID OUTSIDE SHOULDER BEING FORMED TO SEAT ON A SHOULDER WITHIN THE CASINGHEAD, A FIRST STRING OF CASING SECURED TO AND SUSPENDING FROM THE FIRST CASING HANGER, A SECOND CASING HANGER HAVING SEATING SHOULDERS FORMED ON AT LEAST THE OUTSIDE THEREOF, SAID OUTER SHOULDER BEING FORMED TO SEAT ON THE SHOULDER WITHIN SAID FIRST CASING HANGER, A SECOND STRING OF CASING SECURED TO AND SUSPENDING FROM THE SECOND CASING HANGER, AND HOLD-DOWN SLIP MEANS CARRIED OUTWARDLY BY EACH OF SAID CASING HANGERS AND POSITIONED TO ENGAGE THE INNER SURFACE OF SAID CASINGHEAD. 